| Autor: |
W.V George, U Paw, K.T Pruitt, W.O Hossein Ashktorab |
| Rok vydání: |
1989 |
| Předmět: |
|
| Zdroj: |
Agricultural and Forest Meteorology. 46:259-274 |
| ISSN: |
0168-1923 |
| DOI: |
10.1016/0168-1923(89)90068-3 |
| Popis: |
A micro-Bowen ratio system, with β determined from temperature and humidity measurements very close to the soil surface (1 and 6 cm), was tested above bare soil by comparison with evaporation losses from a highly sensitive 6.1-m diameter lysimeter. The results indicated good accuracy in estimation of evaporation ( E ) during 8 days with moist soil-surface conditions, as well as 1 day of second-stage drying conditions when E averaged only 30–40% of a calculated reference crop evapotranspiration. Good agreement between estimated and measured E was also found, using a Bowen ratio system with a chilled mirror hygrometer sensing air sampled at 5 and 85 cm above the soil surface. On one of the study days a second Bowen ratio system (psychrometric with sensors at 5 and 85 cm) was employed as well as eddy-correlation instrumentation for measuring sensible heat flux ( H ), with H used in the energy balance equation to solve for LE . Close agreement with lysimeter-determined E and calculated E from these two systems was noted although in later afternoon hours some divergence occurred, probably produced as upwind soil surfaces developed inhomogeneous surface-moisture conditions. The results suggest that the microsystem approach should be applicable to under-canopy and small-plot studies where traditional methods are impractical. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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